Selfpriming centrifugal pump



March 17, 1964 HIDEKUNI YoKoTA ETAL 3,125,030

SELFPRIMING CENTRIFUGAL PUMP 2 Sheets-Sheet 1 Filed Feb. 19, 1962 March 17, 1964 HlDEKUNl YOKOTA ETAL 3,125,030

SELFPRIMING CENTRIFUGAL PUMP 2 Sheets-Sheet 2 Filed Feb. 19, 1962 United StatesPatent O 3,125,030 SELFPREMING CENTRIFUGAL PUMP Hidekuni Yokota, 671 Yoshiiima-cho, and Shingo Yokota, 1627 Midori-machi, both of Hiroshima-shi, Japan Filed Feb. 19, 1962, Ser. No. 174,132 1 Claim. (Cl. 103- 113) The present invention relates to an improved selfpriming centrifugal pump.

In general, the so-called selfpriming centrifugal pump is so constructed, in order to discharge the air produced in the cavity at the central portion of the impeller, that the water deprived of air bubble is recycled from the bottom part of an air separating chamber provided at the discharge side into a part having a pressure lower than that of the discharge port of the pump, that is, into the pump casing and is again accelerated by the impeller, and the air in the said central cavities is mixed, in a fine bubble state, into the said recycling stream so as to be discharged from the air separating chamber. Such an operation as described above is repeated, whereby an effective discharge of the produced air is attained.

In the above-mentioned selfpriming centrifugal pump, there are various systems for introducing the selfpriming circulation water into the pump casing from the air separating chamber. Accordingly, it has been misunderstood that various kinds of selfpriming pumps exist. However, forms of the conventional selfpriming centrifugal pumps have such disadvantages as that their forms are awkward, their selfpriming function is relatively inferior, and their pumping efficiencies are remarkably sacrificed. It seems that the above-mentioned disadvantages are due to the fact that persons skilled in the art who are interested in ordinary selfpriming pumps have been fascinated by only the aspect of how to create air bubbles and discharge them out of the pumps and are neglecting the problem of the air separator, which actually determines the selfpriming performance. In the selfpriming centrifugal pump, when the pressure difierence between the pressure at the admission port side and the pressure at the discharge side of the pump increases with the progress of the selfpriming action, the central cavity of the impeller is narrowed, so that the air bubble accompanied by the water stream must be of a sufiiciently fine state in order to emerge outward together with a slight radial flow of the said stream against the forcible centrifugal action through a thick rotating water layer formed in the impeller. Furthermore, the said air bubble is further narrowed at the time when it comes to the discharge side, so that it is very diflicult to separate skillfully the said fine air bubble by an insufli cient air separating chamber such as those of the conventional systems. Although the conventional centrifugal pumps do not have selfpriming action, since the said pumps are very simple and have substantially reasonable construction, said pumps have been broadly adopted in spite of the fact that the selfpriming centrifugal pump has an effective selfpriming function, because it is very difficult to solve all of the problems relating to the difiicult selfpriming function and construction. Accordingly, almost all of the selfpriming centrifugal pumps proposed heretofore have the disadvantages that there is a part which is defective for water pumping and makes the cost of the pump very high, and treatment of the pump is very inr 3,125,030 Patented Mar. 17, I964 "ice Said object and other objects of the present invention have been attained by the construction wherein the pump casing is provided with main and auxiliary vortex chambers and the former being larger and the latter being smaller, the rear stream portion of the diffuser of the main vortex chamber is formed to be a vertical, cylindrical form, the outlet opening of the diffuser of the auxiliary vortex chamber is opened into the upper part of the said cylindrical portion so as to be tangential to the internal surface of said portion, and a cavity holder is provided at the lower central portion of the said cylindrical portion.

The details of the present invention as well as the manner in which the objects of the invention may best be achieved will be understood more fully from a consideration of the following description taken in conjunction with the accompanying drawings throughout which the same parts are designated by the same reference numerals, and in which:

FIG. 1 is a side elevational view of an example of the present invention;

FIG. 2 is a plan view of the pump of FIG. 1;

FIG. 3 is a front view of the pump of FIG. 1;

FIG. 4 is a back view of the pump of FIG. 1;

FIG. 5 is a back side elevational view of the pump of FIG. 1;

FIG. 6 is a bottom view of the pump of FIG. 1;

FIG. 7 is a sectional plan view along line VII-VII of FIG. 1;

FIG. 8 is a sectional front view along the line VIl1- VIII of FIG. 1; and

FIG. 9 is a sectional side view along the line IXIX of FIG. 3.

Referring to the drawing, the peripheral part of a pump casing 1 consists of main and auxiliary vortex chambers3 and 4 which are provided at almost opposite positions. The auxiliary vortex chamber 4 is constructed so as to be smaller than the main vortex chamber so that the stream velocity in the said chamber 4 may be large and may be substantially converted to pressure at a dif fuser 6. The diffuser 5 of the main vortex chamber 3 is gradually enlarged and the rear part thereof is formed to be a substantially vertical, cylindrical chamber 7. The outlet opening of the diffuser 6 is opened in the upper part of the said cylindrical chamber 7 of the diffuser 5 so as to be tangential to the internal surface of the said cham her 7. In the lower, central portion of the chamber 7 is a cone-shaped cavity holder which is open at the base of the cone, the apex of the cone being fastened to the bottom of the chamber. The open base end of the cone which is disposed towards the lower central portion of chamber 7 is so sized as to allow a passage between the cavity holder and cylindrical chamber 7. Inside the easing 1 is provided an impeller.

The operation and advantages of the above construction will be described as follows.

In the above construction, the main and auxiliary vortex chambers are designed so that their capacities are, respectively, somewhat larger and somewhat smaller than those corresponding to a predetermined flow capacity, said chambers having their respective diffusers, and these diffusers being joined at their outlet portions. Accordingly, the pump has a pumping performance similar to that of the conventional centrifugal pump filled with water and having the necessary and sufficient flow passage in the normal pumping state. On the other hand, when a large quantity of air is sucked from the admission side, and an air cavity is thereby formed in the central portion of the impeller, water pumping should stop. However, in this time, owing to the combination of the vortex chambers 3, 4 and diffusers 5, 6 having the construction as described above, a circulation of the water in the cylindrical chamber 7 is induced through the members 7-53 passage between the impeller 4'6-7. During the said circulation, the circulating stream is somewhat replaced by or mixed with the channel vortex produced in the impeller, whereby the air in the central cavity is mixed, in a fine bubble state, into the said circulating stream. This circulating stream of water containing the said fine air bubbles is discharged through the diffuser 6, along the internal surface of the cylindrical chamber 7. This stream discharged into the chamber 7 whirls along the internal surface of the chamber 7, so that the air bubbles are urged to and collected in the central portion of the chamber 7 by the centrifugal force of the said whirling action, thus forming an air cavity at the said central portion. Since the cavity holder 8 is provided at the lower end of the said cavity, the lower part of the said cavity extending in the spiral state can be surely protected from recycling, through the diffuser 5, into the pump casing. Accordingly, the water returning into the diffuser through the passage 9 formed by the internal surface of the cylindrical chamber 7 and periphery of the cavity holder 8 is sufficiently deprived or air bubbles, whereby excellent air discharging function is achieved.

It may appear that the construction of the cavity holder 8 and the passage near said holder is very primitive and meaningless, but if said construction were omitted, the selfpriming function could not be attained at all.

As described above, the pump of the present invention has only the construction which is necessary to achieve the pumping function of the centrifugal pump and is not provided with any other construction such as an air separating tank which causes disappearance of the pump and decrease of the pumping effect. In spite of this fact, the

pump of this invention has such a selfpriming function a casing having an internal wall portion defining a substantially cylindricalirnpeller section between the top and bottom thereof; V

a rotating impeller in said section substantially tangent to said Wall portion towards the top thereof so as to define a main involute vortex chamber around the top, one side and the bottom of said section, discharging into the bottom of a first vertically disposed cylindrical diffuser;

an auxiliary vortex chamber formed between said diffuser and the other side of said section,said auxiliary vortex chamber terminating in a second diffuser integral with said auxiliary vortex chamber, said second diffuser discharging into said first diffuser towards the top thereof and tangential thereto; and

a cone-shaped cavity holder in said first diffuser being open at its base, the apex of the cone being fastened to the bottom of said first diffuser, the open end of the cone being disposed towards the lower central portion of said first diffuser allowing a passage between said cone-shaped cavity holder and said first diffuser, said cavity holder acting to prevent air bubbles from recycling down towards the bottom of said first diffuser.

References Cited in the file of this patent UNITED STATES PATENTS Norway Nov. 24, 1958 

